Textbook: If something is “textbook” it means it is a typical or common case.
My 7 year old son often threatens to run away from home when he is upset. It is textbook behavior for a child of that age.

Bend the rules: Bending the rules means to change the rules a little to make them suit your situation.
For example, imagine that the rule is that it is half price drinks (happy hour) from 6-8 pm every night. The waitress comes to your table at 8:01 and says you need to pay full price. You might try to say, “oh come on, you can bend the rules a little can’t you?”

Play hardball: Playing hardball means that you are using a very tough negotiation strategy. If you are playing hardball it means that you are trying your hardest to get exactly what you want. You will be mean and serious if you need to be.
“I’m usually very calm when I ask my boss for a raise and he doesn’t listen to me. I’m going to have to play hardball”.

Call his bluff: If someone is bluffing it means that they are pretending to have a strong position, but they actually have a weak one. In the card game poker, somone with poor cards might bet a lot of money to trick people into believing he has good cards. This is called bluffing. If a wife is angry with her husband she might say, “if you stay out late partying with your friends one more time I’m going to leave you”. She is using this tactic to scare her husband. He might not believe she is that serious and “call her bluff”. That means he will go out with his friends again and see if she will seriously leave him.

In business, an employee might say to the boss, “If I don’t make 50% more money this year then I’m going to leave the company”. If the company doesn’t believe it, they might call his bluff by saying “ok, we can’t afford to pay you that much”. If the company sees that the person is actually going to leave, then they might agree to the 50% increase. If they see that he was bluffing, then they might be able to pay him less.